Most services require user identification. The method for proving the identity is authentication. The typical ways to provide authentication include but are not limited to authentication protocols and transmitted stored or user entered passphrase. This result of the authentication protocol or transmission of a passphrase serves as a credential proving identity. Examples of services that use these authentication methods are: LDAP, HTML documents, UDDI, etc.
For example, the Universal Description, Discovery and Integration (UDDI) architecture provides a service with which businesses can register and then utilize to publish their information as well as seek information about other businesses. LDAP stands for the Lightweight Directory Access Protocol that specifies how global directories should be structured. Directories using LDAP typically require the user to enter a user id and passphrase.
A possible pitfall for clients using these services is their vulnerability to attacks by hackers and impostors. Impostors could insert themselves into the process and usurp information, possibly sensitive, from both the client and the service. This could lead to such problems as theft of monies involved in transactions, identity theft and others.